A number of wrist-mounted radio receivers are known. Such devices are generally combined with a wristwatch and generally provide some type of paging capability. A wrist band, which secures the radio receiver to a wearer's wrist, is generally used to contain an antenna for such a radio receiver. One such receiver is disclosed in U.S. Pat. No. 4,713,808, WATCH PAGER SYSTEM AND COMMUNICATION PROTOCOL, Gaskill et al., Dec. 15, 1987. Another receiver is discussed in U.S. Pat. No. 4,873,527, ANTENNA SYSTEM FOR A WRIST CARRIED PAGING RECEIVER, Tan, Oct. 10, 1989. A radio receiver which is designed for such an application is disclosed in U.S. Pat. No. 4,885,802, WRISTWATCH RECEIVER ARCHITECTURE, Ragan, Dec. 5, 1989. Differential inputs to amplifiers are known, and one such differential input amplifier is disclosed in Signetics Linear Products Corporation specification sheet for Model No. TDA 1574 FM Front-End Integrated Circuit, Nov. 14, 1986. Additionally, a co-pending application entitled AUTOMATIC ANTENNA TUNING METHOD AND APPARATUS, Ser. No. 07/279,952, filed Dec. 5, 1988, discloses amplifiers having differential inputs, having a side thereof grounded. The preceding patents, publications and applications are incorporated herein by reference.
Generally, if a radio antenna is contacted by a conducting object, or by a body, the antenna will be detuned, i.e., the effective length of the antenna will change and the ability of the antenna to receive RF signals in its intended frequency range will be degraded. This tendency of an antenna to detune in the case of wrist-mounted radio receivers is particularly troublesome as the antenna must generally be insulated from the wearer's wrist to prevent or minimize the effect of the contact between the antenna and the wearer's body. Such problems may be overcome by completely insulating the antenna over its length. However, in the case of a watch band which includes a pair of straps ad a buckle located between and joining the two straps, the problem of insulating the buckle while still providing an electrical contact between antenna halves which are carried in the straps requires that the buckle be insulated or that some complicated mechanism be provided to connect the two halves of the antenna. Providing effective insulation for such a buckle, while simultaneously providing a buckle which connects the two straps of a wrist band, thereby providing both physical and electrical connection between the two sections of the antenna, is difficult if not impossible.